Truck tailgate operating mechanism

ABSTRACT

A tailgate operating mechanism for a truck having a dump bed pivoted near the rear end and a tailgate pivoted near the top of the bed, including a means having a cam section and a cam driven section operable by the raising and lowering of the dump bed. The cam section is normally connected to the frame of the vehicle and the section operated by the cam is normally mounted on the underside of the bed near the front thereof where it will contact the cam section when the bed approaches its lowered position.

O Unlted States Patent 11113,572,837

I 1 lnvcmor Joseph Lackey 3,072,438 1/1963 Livingston 298/23(C) Blake z46368 3,404,918 10/1968 Lackey 298/23(ML) 12 1 pp N9 791,001 3,437,3764/1969 Keathly 298/23(C) [22] Filed Jan. I969 Primary Examiner Richard.]Johnson [45] Patented Mar. 1971 Attorneys-Hobbs and Green and Kemon,Palmer &

Estabrook [54] ELE MECHANISM ABSTRACT: A tailgate operating mechanismfor a truck having a dump bed pivoted near the rear end and a tailgate[52] US. Cl t. 298/23 pivoted near the top f the bed including a meanshaving a F- Cl 9 1/26 cam section and a cam driven section operable bythe raising [50] Fleld of Search 298/23 and lowering of the dump The camSection is normally 5 References Cited connected to the frame of thevehicle and the section operated by the cam is normally mounted on theunderside of the bed UNTED STATES PATENTS near the front thereof whereit will contact the cam section 2,261,745 1 1/1941 Sand 298/23(C) whenthe bed approaches its lowered position,

PATENTEU maomn 3572 37 SHEET 1 BF 4 3 [NV/:JN'I'UR.

Q} JOSEPH A LA CAEY BY 7% WM ATTORNEY PATENTEDHARBOIS?! 3572.837

SH[U 3 BF 4 INVIEN'I'OR.

JOSEPH A. LACK: v

BY 7% 3 M 4 TTORNE Y PATENTED man I97! SHEET 0F 4 INVIiNI'UR. JOSEPHA.LACKEY #4 TTORNEY TRUCK TAILGATE OPERATING MECHANISM In the operationof a dump truck to discharge the load, the operator manually releasesthe tailgate, generally by the use of a lever mounted near the forwardend of the bed and connected to the tailgate latch by a mechanicallinkage, and the front end of the bed is then raised by a hydraulicoperating mechanism causing the load to slide from the rear of the bed.After the tailgate has been released and the load discharged, the bed islowered to its original position and the tailgate manually latched inits closed position. In the dumping operations, the tailgate is normallyreleased by the manually operated lever before the bed is raised orfully raised for discharging the load; however, the bed may be fullyraised'before the tailgate is released. In either of these twooperations, the driver is required to leave the cab, or to reachtherefrom and grasp and operate the manual lever to unlatch thetailgate. This is not only inconvenient and time consuming, but alsooften requires the use of substantial physical force to operate thelever, particularly after the front end of the bed has'been elevated. Itis therefore one of the principal objects of the invention to provide areliable operating mechanism for the tailgate of dump trucks, whichutilizes the movement of the truck bed between its raised and loweredpositions for operation of the mechanism, and which automaticallyoperates to relatch the tailgate when the bed is lowered.

Another object of the invention is to provide a versatile tailgateoperating mechanism for dump trucks, which can .be readily adapted tobeds of various types and designs, and which can easily be installed atdifferent locations on the truck bed without changing the basic designand construction of'the mechanism or without changing the bedconstruction in any appreciable manner.

Still another object of the invention is to provide areliable andrelatively simple tailgate operating mechanism of the aforementionedtype which can be operated automatically in conjunction with theoperation of the bed or which can be operated manually when the bed isstationary to either release or latch the tailgate.

Further objects and advantages of the invention will become apparentfrom the following description and accompanying drawings, wherein:

FIG. 1 is a fragmentary side elevational view of a dump truck showingthe bed thereof in a partially elevated position;

FIG. 2 is an enlarged partial cross sectional and side elevational viewof the operating mechanism for the tailgate of the dump truck bed, thesection being taken on line 2-2 of FIG. 3;

FIG. 3 is a top plan view of the tailgate operating mechanism shown inFIG. 2;

FIG. 4 is an elevational and partial cross-sectional view of theoperating mechanism shown in FIG. 3, the section being taken on line 4-4of FIG. 3; and

FIG. 55 is an elevational and crosssectional view similar to that shownin FIG. 4 illustrating the mechanism in a different operating position.

Referring more specifically to the drawings and to FIG. 1 in particular,numeral designates generally a dump truck having a frame l2, a bed 14mountedon the frame by a subframe 16, the subframe being rigidly joinedto the main frame 12 by a plurality of fixtures I8 welded to the sidemembers of the two frames. The bed is pivoted to the subframe by a pivotmeans consisting of laterally disposed members on the bed pivotallyjoined to the subframe by a pivot rod 22 extending through the rear endof the two side members of the subframe and through fixtures 24 on theopposite sides of the frame, the fbrtures being joined to the main frameand subframe bywelding or other suitable securing means. The bed has atailgate 30 pivotally attached to the upper edge of the bedby aforwardly extending lever 32 and pivot means 34 consisting of upwardlyextending fixtures 36 on opposite sides of the bed and corresponding pin33 extending through lever 32 and fixture 36 on each side of the bed.The bottom of the bed extends rearwardly and terminates in a lip 40pivotally connected to the main part of the bottom by a pivoted joint42. The tailgate is hook 50 pivotally connected to the frame 52 of bed Mby a pivot pin 54 extending through the frame members and outwardly tothe edge of the bed where it supports and operates the hook. The hook isshown in its raised position with the tailgate unlatched. When the bedis lowered. the tailgate swings inwardly to the rear edges 56 of the bedand hook rotates downwardly over a pin 60 secured to the lower outeredge of the tailgate, thus latching the gate in its closed position.

The operating mechanism consists essentially of two basic parts, anoperating force transmitting section 70 and an operating cam section 72.The force transmitting section is mounted on the underside of bed 14'near the forward end thereof, and the operating cam section is mountedon subframe 16 beneath the force transmitting section. The two sectionsare interconnected when the bed is in its lowered or substantiallylowered position, and it is this interengagement which operates themechanism to latch and unlatch the tailgate.

Section 70 includes a shaft 74 joumaled in fixtures 76 and 78, which inturn are rigidly mounted on the underside of bed I4. Mounted on theinner end of shaft 74 is a cam follower 80 having a roller 82 rotatablymounted in the bifurcated free end of the arm; The arm is rigidlysecured to shaft 74 and roller 82 engages the cam surface 84 ofoperating cam section 72. The cam surface is provided on the uppersurface of arcuate member 86, which in turn is supported by a flange 88,and forms a rigid track on which roller 812 travels as the bed is movedtoward and away from the cam section. The cam section is secured by aplurality of bolts (not shown) to the side of subframe I6. In order toassure that the cam section follows the cam as the bed is raised, aroller 92 is secured to flange 88 above the surface 84 and is firmlyattached to the cam section by a stub shaft 94 on which the roller isjoumaled. As the bed is lowered, roller 82 engages cam surface 84 andfollows the surface from the right-hand end thereof, as viewed in FIGS.4 and 5, to the left-hand end, as shown in FIG. 4, and, as the bed israised, roller 92 causes lever 80 to return to its downwardly extendingposition illustrated in FIG. 5. Arm 80 is also urged in the directionopposite that produced: by cam surface 84 by a coil spring 97 connectedat one end to support member 76 and at the other end to a collar 98secured to shaft 74 by a set screw 99. The stub shaft on which roller 92is mounted is adjustable along flange 88 as a result of longitudinalslot 96 through which the shaft extends.

Mounted parallel with shaft 74 is a shaft 100 supported by fixtures I02and 104 which are secured rigidly to the underside of bed M. The innerend of shaft 100 is connected to hook 50 of the tailgate latch by rod 66through a bell crank 106 rigidly secured to the end of shaft 100.Rotation of the shaft in a counterclockwise direction, as viewed in FIG.1, shifts rod 66 rearwardly to release the tailgate. A pulley Iii) ismounted on and secured to shaft 74, and a pulley 112 is mounted on shaft100, and these two pulleys are interconnected by a cable 114 whichextends around pulley I I0 and is secured thereto by a clamp I16, andextends around pulley M2, and the end thereof is secured to the pulleyby set screws U8 and 120. A section of cable 114 secured to pulley 112by set screw is connected to a safety spring 122 which in turn isconnected to .the other end of cable I14. Spring I22 is inserted in thecable between the pulleys on the upper side thereof, to prevent damageto the mechanism in the event the tailgate is not properly seated or isprevented from closing by a foreign object, when thebed is fully loweredand lever 30 has been moved to the position shown in FIG. 2. The springalso retains the cable in a taut condition during normal operation.

Pulley 112 is operatively connected to shaft 100 by a clutch mechanismconsisting of an axially movable collar having teeth 132 thereon forengagement with teeth 134 on the adjacent side of pulley 112. The clutchportion 132 is urged into engagement with the clutch portion formed byteeth 1% by a coil spring 136 reacting between support member ltld andcoilar 130. The collar may be held in either its engaged or dislatchedat the bottom by a latch mechanism consistingtof a 75 engaged positionby a set screw I38, extending through the collar and engaging the shaft.The shaft 100 may be rotated manually by hand lever 140 to move lever106 angularly in the direction to either release or latch the tailgateafter clutch collar 130 has been withdrawn from clutch teeth 134. Whenthe clutch elements consisting of teeth 132 and 134 are engaged, themechanism operates automatically in both directions as the cam and camlever operate to release and latch the tailgate as the bed is raisedfrom its fully downward position to a partially elevated position.

in the operation of the present tailgate operating mechanism, startingwith the bed in its lowered position and the tailgate held in itslatched position with hook 50 extending downwardly and rearwardly overpin 60, the bed elevating mechanism is operated to tilt the bed upwardlyin the manner illustrated in FIG. 1. As the bed moves upwardly from itsfully lowered position, cam roller 82 moves along cam surface 84 in thedirection to rotate lever 80 in a counterclockwise direction, as viewedin FIGS. 4 and 5, thus causing rotation of shaft 74, this movement beingassured by roller 92 and spring 97. As shaft 74 is rotated, it rotatespulley 110 which, through cable 114, in turn rotates pulley 112. Withclutch elements 132 and 134 engaged, shaft 100 in turn moves lever 106angularly to shift rod 66 rearwardly, thus raising hook 50 and releasingthe tailgate. As the bed is tilted further upwardly, the tailgate isfree to swing outwardly, permitting the load to discharge from the bed.Upon return of the bed to its lowered position, roller 82 on lever 80engages cam surface 84 which causes the lever to move in a clockwisedirection as viewed in FIGS. 4 and 5, thus rotating shaft 74, andpulleys 110 and 112 in the clockwise direction. The rotation of pulley112 is transmitted through clutch elements 132 and 134 to shaft 100,which in turn moves lever 106 angularly in the direction to shift rod 66to the left, as viewed in FIG. l, thereby causing hook 511 to movedownwardly over pin 60 on the closed tailgate 30. The connection fromarm 80 through shaft 74, pulleys 110 and 112, collar 130 and shaft 100is a positive connection, with the exception of spring 122, and, sinceshaft 100 is connected to hook 50 by a direct mechanical linkageconsisting of lever 106 and rod 66, the hook is positively held in itslatched position, when the cam arm 80 is in the position on cam surface84, of member 86, as illustrated in FIG. 4. Safety spring 122 willoperate to relieve any excess forces in the event the tailgate fails toseat.

While only one embodiment of the present truck tailgate operatingmechanism has been described in detail herein, various changes andmodifications may be made without departing from the scope of theinvention.

lclaim:

l. A tailgate operating mechanism for a truck having a frame and a bedpivotally connected to the frame at the rear end thereof and a tailgatepivotally connected at the top to the rear of the bed, said mechanismcomprising a latch for releasably retaining the tailgate in closedposition, a latch operating means having a section with a cam and asection with a cam engaging means, one of said sections being connectedto the frame and the other of said sections being mounted on the bed,said last mentioned section including two spaced parallel shafts withthe cam engaging means being connected to one of said shafts and alinkage connected to the other of said shafts and to said latch forreleasing and locking the tailgate as the bed is raised from and loweredto its lowered position, and a force transmission means interconnectingsaid shafts so that movement of said cam engaging means by said camoperates said linkage.

2. A tailgate operating mechanism as defined in claim 1 in which thesection having said cam is connected to the truck frame and the sectionhaving the cam engaging means is mounted on the bed.

3. A tailgate operating mechanism as defined in claim 1 in which thesection having said cam includes a guide roller to move the cam engagingmeans to cause positive movement of said cam engaging means as the truckbed is raised. I

4. A tailgate operating mechanism for a truck as defined in claim 1 inwhich said linkage includes a lever connected to the end of therespective shaft and a rod moved generally longitudinally for releasingand latching the tailgate.

5. A tailgate operating mechanism for a truck as defined in claim 1 inwhich said force transmission means consists of a pulley mounted on eachshaft and a cable interconnecting said pulleys.

6. A tailgate operating mechanism as defined in claim 5 in which adisengageable clutch connects said force transmission means to the shaftto which said linkage is connected.

7. A tailgate operating mechanism as defined in claim 6 in which amanually operated means is connected to the shaft having said clutch.

8. A tailgate operating mechanism as defined in claim 7 in which thesection having said cam includes a guide roller to move the cam engagingmeans to cause positive movement of said cam engaging means as the truckbed is raised.

1. A tailgate operating mechanism for a truck having a frame and a bedpivotally connected to the frame at the rear end thereof and a tailgatepivotally connected at the top to the rear of the bed, said mechanismcomprising a latch for releasably retaining the tailgate in closedposition, a latch operating means having a section with a cam and asection with a cam engaging means, one of said sections being connectedto the frame and the other of said sections being mounted on the bed,said last mentioned section including two spaced parallel shafts withthe cam engaging means being connected to one of said shafts and alinkage connected to the other of said shafts and to said latch forreleasing and locking the tailgate as the bed is raised from and loweredto its lowered position, and a force transmission means interconnectingsaid shafts so that movement of said cam engaging means by said camoperates said linkage.
 2. A tailgate operating mechanism as defined inclaim 1 in which the section having said cam is connected to the truckframe and the section having the cam engaging means is mounted on thebed.
 3. A tailgate operating mechanism as defined in claim 1 in whichthe section having said cam includes a guide roller to move the camengaging means to cause positive movement of said cam engaging means asthe truck bed is raised.
 4. A tailgate operating mechanism for a truckas defined in claim 1 in which said linkage includes a lever connectedto the end of the respective shaft and a rod moved generallylongitudinally for releasing and latching the tailgate.
 5. A tailgateoperating mechanism for a truck as defined in claim 1 in which saidforce transmission means consists of a pulley mounted on each shaft anda cable interconnecting said pulleys.
 6. A tailgate operating mechanismas defined in claim 5 in which a disengageable clutch connects saidforce transmission means to the shaft to which said linkage isconnected.
 7. A tailgate operating mechanism as defined in claim 6 inwhich a manually operated means is connected to the shaft having saidclutch.
 8. A tailgate operating mechanism as defined in claim 7 in whichthe section having said cam includes a guide roller to move the camengaging means to cause positive movement of said cam engaging means asthe truck bed is raised.